Invested around $3K in ngtlds, lots of research and trying to make sure keyword.Whatever made sense.
Sold one for $10K, one for $3.4K and a couple of others in mid $xxx so well in to profit but I think luck more than judgement.
Dropped most but retained a few where the renewal fees are acceptable versus potential resale.That applies across the board with my dwindling portfolio.
Looking at recent figures on new releases it looks like in general ngtlds are going belly up rapidly, maybe hang on to your IDN a bit longer!